Powder paint with epoxy and amide copolymer with anhydrides and hydroxy acids

ABSTRACT

Improved powder coating compositions are disclosed which comprise a particulate mixture of (1) a qualitative difunctional copolymer of about 5 to 20 weight percent of a glycidyl ester of a monoethylenically unsaturated acid, about 2 to about 10 weight percent of a monomeric alpha-beta olefinically unsaturated amide and about 70 to about 93 weight percent of other monoethylenically unsaturated monomers consisting essentially of monofuctional, monomers selected from the group consisting of esters of a C 1  - C 8  monohydric alcohol and acrylic acid, esters of a C 1  - C 8  monohydric alcohol and methacrylic acid and C 8  - C 12  monovinyl hydrocarbons, (2) an anhydride crosslinking agent selected from the group consisting of (a) monomeric anhydrides of dicarboxylic acids and (b) homopolymers of monomeric anhydrides of dicarboxylic acids and present in an amount that provides about 0.3 to about 1.2 anhydride groups for each functional group on said copolymer, and (3) a hydroxy carboxylic acid having a melting point in the range of about 40° to about 150° C. and present in an amount such as to provide about 0.1 about 0.4 carboxyl groups per functional group on said copolymer.

This application is a Continuation-In-Part of application Ser. No.394,877 filed Sept. 6, 1973 now abandoned.

BACKGROUND OF THE INVENTION

Powder coating compositions are extremely desirable for use in paintingsubstrates in that they are essentially free of organic solventsconventionally utilized in liquid paint systems. Thus, they give offlittle, if any, volatile material to the environment when heat cured.

Powder coatings comprising (1) a copolymer of a glycidyl acrylate andother monofunctional olefinically unsaturated monomers, (2) adicarboxylic acid crosslinking agent and (3) a polymeric flow controlagent was heretofore described in U.S. Pat. No. 3,752,870 issued Aug.14, 1973 to Santokh S. Labana.

Powder coating materials comprising (1) a copolymer of a glycidylacrylate and other monofunctional olefinically unsaturated monomers, (2)a crosslinking agent comprising a mixture of a monocarboxylic acid and adicarboxylic acid, and (3) a polymeric flow control agent wereheretofore described in U.S. Pat. No. 3,730,930 issued May 1, 1973 toSantokh S. Labana.

Powder coating materials comprising (1) a copolymer of a glycidylacrylate and other monofunctional olefinically unsaturated monomers, (2)an anhydride (monomeric and polymeric) crosslinking agent, and (3) apolymeric flow control agent was heretofore described in U.S. Pat. No.3,781,379 issued Dec. 25, 1973 to Santokh S. Labana and Ares N.Theodore, a coinventor herein.

THE INVENTION

It now has been discovered that the addition of hydroxy carboxylic acidsto an epoxy-functional and amide functional copolymer and an anhydridecrosslinker powder coating system provides coating powders withexcellent flowability and functional group conversion upon curing evenat temperatures lower than those conventionally used for curing acrylicbased powder coatings. The coatings obtained by baking these powders at300° F. for 20-30 minutes have excellent gloss, adhesion to metals,hardness and solvent resistance. Further, aside from crosslinkingcapabilities, the use of the dual functionality of the hydroxycarboxylic acids in combination with the anhydride and the dualfunctionality of the aforementioned copolymer provides a powder mixcharacterized by unusual polarity. This provides compatibility (aidshomogeneous mixing) of the complete coating composition includingpigment dispersion.

These powders are effectively prepared by spray drying in that theyresist phase separation. They may also be processed by melt blending andvacuum drying techniques. They are easily and effectively mixed byextrusion or mill rolling. Further, the need for an antistatic agent iseliminated when a film depth of less than 4 mils (0.004 in.) is to beapplied.

Except in those instances wherein a specific compound is named, the term"acrylate" is used in this specification to include esters of bothacrylic and methacrylic acid, i.e., acrylates and methacrylates.

DETAILED DESCRIPTION OF THE INVENTION

Epoxy and amide functional copolymers suitable for use in the powdercoating materials of this invention are readily formed by conventionalfree radical induced polymerization of suitable alpha-beta olefinicallyunsaturated monomers. These copolymers having both epoxide groups andamide groups are potentially self-crosslinking but the epoxy-amidereaction is very slow and requires large amounts of catalyst toaccelerate the curing reaction. Thus, in this invention, a crosslinkingagent, i.e., a hydroxy carboxylic acid and an anhydride, are added tothe paint binder system.

The copolymers used in this invention contain between about 5 and about20, preferably between 8 and 15, weight percent of a glycidyl ester of amonoethylenically unsaturated carboxylic acid, e.g., glycidyl acrylateand glycidyl methacrylate. These monomers provide the copolymer with itsepoxy functionality. The amide functionality is provided byincorporating in the unsaturated monomer polymerization mix about 2 toabout 10 weight percent of an alpha-beta olefinically unsaturated amide,e.g., acrylamide and methacrylamide. The alpha-beta olefinicallyunsaturated amide is preferably acrylamide or methacrylamide.

The remainder of the copolymer consists essentially of monofunctional,alpha-beta olefinically unsaturated monomers. These can be acrylates ora mixture of acrylates and monovinyl hydrocarbons. Preferably, in excessof 50 weight percent of the copolymer monomers are esters of a C₁ - C₈monohydric alcohol and acrylic or methacrylic acid, i.e., methylmethacrylate, ethyl acrylate, butyl acrylate, butyl methacrylate, hexylacrylate, and 2-ethyl hexyl methacrylate. C₈ - C monovinyl hydrocarbonssuch as styrene, alpha methyl styrene, vinyl toluene, t-butyl styrene,chlorostyrene, and alpha methyl styrene are suitable for use butpreferably comprise less than 50 weight percent of the copolymer. Othervinyl monomers such as vinyl chloride, acrylonitrile, methacrylonitrileand vinyl acetate may be used as modifying monomers. When employed thesecomprise between 0 and 30 percent by weight of the monomer mixture.

The epoxy-functional and amide-functional copolymers used in thesecoating compositions have a glass transition temperature in the range of40° to 90° C., preferably between 50° and 80° C., and a molecular weight(M_(n)) in the range of about 1500 to about 15,000, preferably about2500 to about 6000.

In preparing this copolymer, the epoxy-functional monomer, e.g.,glycidyl methacrylate and the amide-functional monomer, e.g.,methacrylamide, are mixed with the aforementioned ethylenicallyunsaturated remainder monomers and reacted by conventional free radicalinitiated polymerization in such proportions as to obtain the copolymerfor the powder coating compositions. Thus, when the preferredethlenically unsaturated remainder monomers are used with theepoxy-functional monomer and the amide-functional monomer to form thecopolymer, the epoxy-functional monomer, e.g., glycidyl methacrylate, ispresent in the copolymer from about 5 weight percent to about 20 weightpercent, the amide-functional monomer, e.g., methacrylamide is presentin the copolymer from about 2 to about 10 weight percent, and thepreferred remainder monomers are present from about 93 to about 70weight percent. Generally, a free radical initiator is needed to inducethe polymerization reaction. A large number of free radical initiatorsare known to the art and are suitable for this purpose. These includebenzoyl peroxide, lauryl peroxide, t-butylhydroxyperoxide,acetylcyclohexane sulfonyl peroxide, diisobutyryl peroxide, di-(2-ethylhexyl peroxydicarbonate, di-isopropyl peroxydicarbonate,t-butylperoxypivalate, decanoyl peroxide, azobis (2-methylpropionitrile,etc. The polymerization is preferably carried out in solution using asolvent in which the epoxy-functional, amide-functional copolymer issoluble. Toluene, xylene, dioxane, butanone, etc., are suitable solventsfor this polymerization. If the epoxy-functional, amide-functionalcopolymer is prepared in solution, the solid copolymer can beprecipitated by pouring the solution at a slow rate into a non-solventfor such copolymer such as hexane, octane or water under a suitableagitation condition. The copolymer thus obtained is further dried sothat it contains less than three percent of the materials thatvolatilize at the temperatures used for baking the coatings.

These copolymers can also be prepared by emulsion polymerization,suspension polymerization, bulk polymerization or their suitablecombinations. In these methods of preparing the copolymers, chaintransfer agents may be required to control the molecular weight of thecopolymer to a desired range. The solid copolymers obtained by thesemethods must also be dried to contain less than three percent of thematerials that volatilize at the temperatures used for baking thecoatings.

For powder coating applications, both molecular weight and molecularweight distribution of the epoxy-functional, amide-functional copolymerare important. While the molecular weight (M_(n)) range extends fromabout 1500 to about 15,000, the copolymer component must not containsignificant amounts of higher molecular weight fractions. No more than 5percent of the copolymer should be of molecular weight greater than20,000. The molecular weight distribution as measured by the ratio ofweight average to number average molecular weight (M_(w) /M_(n)) shouldbe in the range of 1.6 to 3.0. The preferred range of molecular weightdistribution as in the range of 1.7 to 2.2.

These powder coating compositions include as crosslinking agents for theaforedescribed copolymers both hydroxy carboxylic acids and anhydrides,preferably polyanhydrides.

Hydroxy carboxylic acids with melting points in the range of about 40°to about 150° C. are suitable for use as crosslinking agents in thesepowders. These include such hydroxy carboxylic acids as 12-hydroxystearic, 10-hydroxy octadecanoic acid, 3-hydroxy octadecanoic acid,2-hydroxy myristic acid, 2-hydroxy octadecanoic acid, etc.

The anhydride crosslinking agent may be either monomeric or polymeric,preferably polymeric, and is employed in an amount such as to provideabout 0.3 to about 1.2 anhydride groups per functional group, i.e.,epoxy and hydroxy groups in the copolymer. The hydroxy carboxylic acidsare employed in an amount of about 0.1 to about 0.4 hydroxy carboxylicacid groups per functional group.

Where the anhydride is monomeric, the preferred anhydrides are selectedfrom the group consisting of phthalic anhydride, p-chloro phthalicanhydride, tetrabromo phthalic anhydride, cyclohexane- 1,2 -dicarboxylicanhydride, 4-methylhexane- 1,2 -dicarboxylic anhydride, cyclopentane-1,2 -dicarboxylic anhydride, dicarboxylic anhydride, dodecyl succinicanhydride, succinic anhydride, maleic anhydride, methyl succinicanhydride and azelaic anhydride. In general, the preferred monomericanhydrides are those which are ring compounds having a melting point inthe range of about 35° to 140° C.

Where the anhydride is polymeric, the preferred polyanhydrides arepolyadipic anhydride, polyazelaic anhydride, and polysebasic anhydridebut other having a polymeric molecular weight up to 5000 are useful.Those having a polymeric molecular weight in the range of about 1000 toabout 2500 are preferred.

These powder coating compositions advantageously contain a flow controlagent as a part of the powder coating mixture. The flow control agent isa polymer having a molecular weight (M_(n)) of at least 1000 andadvantageously comprises between 0.05 and 4.0 weight percent of themixture. The flow control agent has a glass transition temperature atleast 20° C. below the glass transition temperature of the mixture'scopolymer.

One group of suitable flow control agents are acrylic polymers.Preferred acrylic polymers which may be used for the flow control agentare polylauryl acrylate, polybutyl acrylate poly (2-ethylhexylacrylate), polylauryl methacrylate and polyisodecyl methacrylate.

The flow control agent may also be a fluorinated polymer having asurface tension, at the baking temperature of the powder, lower thanthat of the copolymer utilized in the mixture. Preferred flow controlagents, if the agent is a fluorinated polymer are esters ofpolyethyleneglycol or polypropyleneglycol and fluorinated fatty acids.For example, an ester of polyethyleneglycol of molecular weight of over2500 and perfluoro octanoic acid is a useful flow control agent.Polymeric siloxanes of molecular weight of over 1000 (advantageously1000 to 20,000) may also be used, e.g., polydimethyl siloxane orpolymethylphenyl siloxane.

A coating composition formed in accordance with the teachings of thisinvention may include a small eight percent of a catalyst in order toincrease the crosslinking rate of the powder coating composition at thebaking temperature thereof. Baking temperatures will ordinarily be inthe range of 130° to 200° C. and the catalyst should produce a gel timefor the powder coating composition at the baking temperature to be usedis at least 1 minute but no greater than 20 minutes. This gel time ispreferably in the range of 1 to 12 minutes and most preferably betweenabout 2 and about 8 minutes at the baking temperature.

Some catalysts which are suitable for use in the powder coatingcompositions include tetraalkylammonium salts, imidazole type catalyst,tertiary amines and metal salts of organic carboxylic acids. Thetetraalkylammonium salt catalysts include the following: tetrabutylammonium chloride (bromide or iodide), tetraethyl ammonium chloride(bromide or iodide), trimethylbenzylammonium chloride, dodecyl dimethyl(2-phenoxyethyl) ammonium bromide, diethyl (2-hydroxy ethyl) methylammonium bromide. Suitable catalysts of the imidazole type include:2-methyl-4-ethyl imidazole, 2-methyl imidazole, imidazole, 2-[(N-benzylanilino) methyl] - 2 -imidazoline phosphate, and2-benzyl-2-imidazoline hydrochloride. Suitable tertiary amine catalystsfor the powder coating compositions of this invention include:triethylenediamine, N,N-diethylcyclohexylamine, and N-methyl morpholine.The metal salts of organic carboxylic acid which are catalysts for thepowder coatings of this invention include, but are not limited to:stannous octoate, zinc naphthenate, cobalt naphthebate, zinc octoate,stannous 2-ethylhexoate, phenylmercuric propionate, lead neodecanoate,dibutyl tin dilaurate and lithium benzoate.

The catalyst used in an individual powder coating composition isgenerally solid at room temperature and has a melting point of from 50°to 200° C.

Conventional non-metallic and metallic pigments can be used with thesepowder coating compositions. Such are conventionally employed in anamount such as to constitute between about 6 and about 35 weight percentof the total mixture depending on the pigment selected and the glossrequired for the baked coating.

Since individual powder coating compositions of this invention can beapplied to an article to be painted by electrostatic methods, one maydesire to include a small weight percentage of an antistatic agent insuch compositions. In particular, the antistatic agent is included in arange from 0.05 weight percent of the total powder composition. Suitableantistatic agents include, but are not limited to, tetraalkylammoniumsalts as discussed previously and which also serve as catalysts. Othersuitable antistatic agents include: alkylpoly (ethyleneoxy) phosphate oralkylauryl poly (ethyleneoxy) phosphate; polyethyleneimine, poly(2-vinyl pyrollidone), pyridinium chloride, poly (vinyl pyridiumchloride), polyvinyl alcohol or inorganic salts.

A plasticizer may be used in a powder coating composition of thisinvention if desired. The type of plasticizers used very often includeadipates, phosphates, phthalates, sebacates, polyesters derived fromadipic acid or azelaic acid, and epoxy or epoxidized plasticizers. Someof these plasticizers are: dihexyl adipate, diisooctyl adipate,dicyclohexyl adipate, triphenylphosphate, tricresylphosphate,tributylphosphate, dibutylphthalate, dioctylphthalate, butyl octylphthalate, dioctyl sebacate, butyl benzyl sebacate, dibenzyl sebacate,butanediol- 1,4 -diglycidyl ether, diglycidyl ether of bisphenol A andits polymers and cellulose acetate butyrate.

Having described the various materials which are employed in formulatingthe powder coating compositions of this invention, a plurality ofexamples are hereinafter set forth to illustrate various individualpowder coating compositions. Illustrated copolymers vary in molecularweight from about 1500 to about 15,000.

EXAMPLE 1

An epoxy-functional, amide-functional copolymer is prepared from thebelow listed components in the manner hereinafter described:

    ______________________________________                                                                  Percent by Weight                                   Reactants     Amounts, grms.                                                                            of Total Reactants                                  ______________________________________                                        glycidyl methacrylate                                                                       225.0       15                                                  methacrylamide                                                                              75.0        5                                                   butyl methacrylate                                                                          600.0       40                                                  styrene       75.0        5                                                   methyl methacrylate                                                                         525.0       35                                                  ______________________________________                                    

The above mentioned monomers are admixed in the proportions above setforth and 70.0 grams (4.5% based on combined weights of reactants) of2,2' -azobis-(2-methyl propionitrile), hereinafter called AIBN, areadded to the monomer mixture. The solution is added dropwise over a 3hour period into 1500 ml. toluene at 100° - 108° C. under nitrogenatmosphere. Then 0.4 grams of AIBN dissolved in 10 ml. of acetone areadded over 1/2 hour period and refluxing is continued for 2 additionalhours.

The toluene-polymer solution is diluted in 1500 ml. acetone andcoagulated in 16 liters of hexane. The white powder is dried in a vacuumoven at 55° C. for 24 hours. This copolymer has molecular weight --M_(w) /M_(n) = 6750/3400 and the molecular weight per epoxy group, WPE,is 1068.

The prepolymer in the amount of 47.0 grams is ball-milled with 2.5 gramsof 12-hydroxy stearic acid, 6.2 grams of poly (azelaic anhydride), 0.45grams of poly (2-ethylhexyl acrylate) of M_(n) = 9000, 5.5 grams oftitanium dioxide and 4.5 grams of Ferrite yellow for 5 - 10 hours. Thefine powder mixture is mill-rolled for 15 minutes at 100° C. or extrudedwith a twin screw extruder. The resulting melt is granulated andpulverized to particles of 10 - 50 micron range.

The resulting powder obtained in this manner exhibits excellentflowability and is sprayed electrostatically on a grounded steel panelby using electrostatic powder spray gun operating at 50 KV chargingvoltage. After deposition of the powder, the panel is baked at 300° F.for 30 minutes.

The glossy coating obtained on the panel exhibits good adhesion toprimed or unprimed steel panels, hardness and flexibility. This coatingapplied to other substrates such as glass, brass, zinc, aluminum, copperand bronze also demonstrates good adhesion. The coating obtained is notsoluble in gasoline, xylene, methyl ethyl ketone and toluene.

EXAMPLE 2

The procedure of Example 1 is repeated. The same copolymer (M_(w) /M_(n)= 6750/3400, WPE = 1068) is used in the preparation of a second powdercoating composition. Here, 47.0 grams of this copolymer are combinedwith the following components:

    ______________________________________                                        poly (azelaic anhydride)                                                                            7.0     grams                                           1 2 - hydroxystearic acid                                                                           1.5     "                                               titanium dioxide      5.5     "                                               Ferrite yellow        4.5     "                                               poly (lauryl acrylate) - M.sub.n =8000                                                              0.45    "                                               ______________________________________                                    

All components are ball-milled for four hours and mill-rolled for 15minutes at 105° C. The material is granulated and pulverized to particlesize range of 10-50 microns. On melting, this powder levels very welland gelled in 8 minutes at 300° F.

Cured coatings of this powder on steel panels, i.e., deposited and curedaccording to the procedure of Example 1, exhibit excellent appearance.They exhibit high impact strength. Their solvent resistance in thesolvents heretofore mentioned in Example 1 is very good.

EXAMPLE 3

The copolymer of Example 1 is used in the formulation of another powdercoating composition. Forty-seven (47.0) grams of this copolymer arecombined with the following chemicals:

    ______________________________________                                        poly (azelaic anhydride)                                                                            5.0     grams                                           12 - hydroxystearic acid                                                                            5.0     "                                               titanium dioxide      5.5     "                                               Ferrite yellow        4.5     "                                               poly (butyl acrylate - M.sub.n =9000                                                                0.5     "                                               tetrabutyl ammonium chloride                                                                        0.04    "                                               ______________________________________                                    

The mixture is processed as in Example 1 and converted to a powder ofcorrect particle size. Then it is sprayed on grounded steel panels andcured at 300° F. for 20 minutes.

The cured coating is glossy and smooth. The adhesion and reverse impactproperties of these coatings are good as are their resistance to theorganic solvents mentioned in Example 1.

EXAMPLE 4

An epoxy-functional and amide-functional copolymer is prepared from thefollowing materials:

    ______________________________________                                                                Percent By Weight                                     Reactants       Grams   of Total Reactants                                    ______________________________________                                        glycidyl methacrylate                                                                         20.0    10.0                                                  methacrylamide  10.0    5.0                                                   butyl methacrylate                                                                            90.0    45                                                    methyl methacrylate                                                                           70.0    35                                                    styrene         10.0    5                                                     ______________________________________                                    

To this mixture are added 10 grams of AIBN (5% by weight of reactants).The polymerization and isolation of the polymer is carried out as inExample 1. The molecular weight of this copolymer is determined to beM_(w) /M_(n) = 5860/3350 and its glass transition temperature (Tg) is53° C.

Forty-seven grams of this copolymer are combined with the followingmaterials:

    ______________________________________                                        poly (azelaic anhydride)                                                                            5.0     grams                                           10-hydroxyoctadecanoic acid                                                                         5.0     "                                               titanium dioxide      6.0     "                                               Ferrite yellow        5.0     "                                               poly (isododecyl methacrylate)                                                                      0.6     "                                               tetrabutyl ammonium iodide                                                                          0.07    "                                               ______________________________________                                    

The mixture of all of these components is ball-milled for 5 hours. Thenit is combined with acetone-methylene chloride solvent (1:1 by volume)and ball-milled for another 5 hours. After evaporation of the solventand granulation of the powder to a particle size range of 10 - 50microns, grounded steel panels are sprayed with this powder and cured at300° F. for 30 minutes. These coatings demonstrate excellent gloss andsurface smoothness.

EXAMPLE 5

An epoxy-functional and amide-functional copolymer is prepared from thefollowing materials:

    ______________________________________                                                                 Percent By Weight                                    Reactants       Grams    of Total Reactants                                   ______________________________________                                        glycidyl methacrylate                                                                         40.0     20.0                                                 methacrylamide  4.0      2.0                                                  butyl methacrylate                                                                            80.0     40.0                                                 methyl methacrylate                                                                           66.0     33.0                                                 styrene         10.0     5.0                                                  ______________________________________                                    

Fourteen grams of AIBN are added to the monomer mixture. Thepolymerization and isolation of the polymer are carried out using thesame procedures used in Example 1.

Forty-seven grams of this copolymer are combined with the followingmaterials:

    ______________________________________                                        poly (sebasic anhydride)                                                                              8.0     grams                                         3-hydroxyoctadecanoic acid                                                                            5.0     "                                             titanium dioxide        6.0     "                                             Ferrite yellow          5.0     "                                             poly (2-ethylhexyl acrylate)-M.sub.n =8500)                                                           0.6     "                                             trimethyl benzyl ammonium chloride                                                                    0.06    "                                             ______________________________________                                    

All of the foregoing ingredients are mixed together and processed inaccordance with the procedure of Example 1 to obtain a powder coatingcomposition. This powder is sprayed on panels and cured at 300° F. for20 minutes.

The coatings obtained from this powder exhibits good adhesion to steel,glass, aluminum, zinc and bronze. It also demonstrates good scratchresistance and good resistance to the organic solvents mentioned inExample 1.

EXAMPLE 6

The epoxy-functional, amide-functional copolymer of Example 1 (M_(w)/M_(n) = 6750/3400, WPE = 1068) is used for the preparation of anotherpowder coating wherein 50.0 grams of this copolymer are combined withthe following ingredients:

    ______________________________________                                        glutaric anhydride    5.0     grams                                           2-hydroxy myristic    3.0     "                                               polyethylene glycol perfluoro                                                 octanoate (M.sub.n =3400)                                                                           0.7     "                                               tetrabutyl ammonium bromide                                                                         0.05    "                                               titanium dioxide      7.0     "                                               ultramarine blue      3.0     "                                               ______________________________________                                    

These ingredients are mixed together and processed in accordance withthe procedure of Example 1 to obtain a powder coating composition. Thispowder coating composition is sprayed on various test panels. Thecoatings obtained after curing the coatings at a temperature of 300° F.for 25 minutes are glossy and exhibit good adhesion to the panels.

EXAMPLE 7

The epoxy-functional and amide-functional copolymer of Example 1 (M_(w)/M_(n) = 6750/3400, WPE = 1068) is employed for the preparation of thispowder coating. Fifty grams of this copolymer are combined with thefollowing materials:

    ______________________________________                                        succinic anhydride     5.2     grams                                          2-hydroxyoctadecanoic acid                                                                           3.0     "                                              tetraethyl ammonium iodide                                                                           0.07    "                                              poly (lauryl acrylate) - (M.sub.n =8000)                                                             0.6     "                                              titanium dioxide       6.0     "                                              Phthalocyanine Blue    4.5     "                                              ______________________________________                                    

The above ingredients are mixed together and processed in accordancewith the procedure of Example 1 to obtain a powder coating composition.This powder coating composition is sprayed on various test panels andcured at 340° F. for 25 minutes. The coatings demonstrate good adhesionand appearance.

EXAMPLE 8

The procedures of Examples 1 - 7 are repeated with the single exceptionthat an equimolar amount of glycidyl acrylate is substituted for theglycidyl methacrylate used as a constituent of the epoxy-functional,amide-functional copolymer.

EXAMPLE 9

The procedures of Examples 1 - 7 are repeated with the single exceptionthat an equimolar amount of acrylamide is substituted for themethacrylamide used as a constituent of the epoxy-functional,amide-functional copolymer.

EXAMPLE 10

An epoxy-functional, amide-functional copolymer is produced using themethod of Example 1 and the following materials:

    ______________________________________                                        Reactants          Percent by Weight                                          ______________________________________                                        glycidyl methacrylate                                                                            5                                                          methacrylamide     10                                                         styrene            5                                                          butyl methacrylate 40                                                         methyl methacrylate                                                                              40                                                         ______________________________________                                    

With these materials, AIBN in the amount of 0.8% by weight of thereactants is employed.

This copolymer in the amount of 47.0 grams was compounded with thefollowing materials:

    ______________________________________                                        poly (azelaic anhydride)                                                                            3.1         grams                                       10 - hydroxy stearic acid                                                                           3.3         "                                           poly (2-ethylhexyl acrylate)                                                                        0.43        "                                           titanium dioxide      5.5         "                                           Ferrite yellow        4.5         "                                           ______________________________________                                    

The mixture is processed to the preparation of a sprayable coatingmaterial following the same procedure used in Example 1. This materialis sprayed on substrates and cured as in Example 1. The coatings exhibitgood appearance and good adhesion.

EXAMPLE 11

An epoxy-functional, amide-functional copolymer having molecular weightof about 1500 prepared using the method of Example 1 from the followingmaterials:

    ______________________________________                                        Reactants          Percent by Weight                                          ______________________________________                                        glycidyl methacrylate                                                                            14                                                         methacrylamide     6                                                          butyl methacrylate 40                                                         methyl methacrylate                                                                              40                                                         ______________________________________                                    

With these materials, there are used 7 grams of AIBN.

This copolymer is compounded into a coating material using the methodsand materials of Example 1, sprayed upon a metal substrate as in Example1, and cured as in Example 1. In this instance, 47 grams of thiscopolymer are used with 2.5 grams of poly (azelaic anhydride) and 2.5grams of 12 - hydroxystearic and 1 gram of stannic chloride.

EXAMPLE 12

An epoxy-functional, methacrylamide-functional copolymer havingmolecular weight of about 15,000 is prepared using the method of Example1 from the following materials:

    ______________________________________                                        Reactants          Percent by Weight                                          ______________________________________                                        glycidyl methacrylate                                                                            8                                                          methacrylamide     2                                                          butyl methacrylate 40                                                         methyl methacrylate                                                                              50                                                         ______________________________________                                    

With these materials, there are used 0.8 grams of AIBN.

This copolymer is compounded into a coating material using the methodsand materials of Example 1, sprayed upon a metal substrate as in Example1 and cured as in Example 1. In this instance, 47 grams of thiscopolymer, are used with 6.0 grams of poly (azelaic anhydride) and 3.0grams of 12-hydroxystearic acid.

EXAMPLE 13

The procedure of Example 1 is repeated except for the difference thatthe copolymer is formed from the following materials:

    ______________________________________                                        Reactants          Percent by Weight                                          ______________________________________                                        glycidyl methacrylate                                                                            15                                                         methacrylamide     5                                                          vinyl chloride     20                                                         vinyl toluene      5                                                          ethyl acrylate     5                                                          butyl acrylate     25                                                         methyl methacrylate                                                                              25                                                         ______________________________________                                    

EXAMPLE 14

The procedure of Example 1 is repeated except for the difference thatthe copolymer is formed from the following materials:

    ______________________________________                                        Reactants          Percent by Weight                                          ______________________________________                                        glycidyl methacrylate                                                                            15                                                         methacrylamide     5                                                          t-butyl styrene    5                                                          chlorostyrene      10                                                         acrylonitrile      5                                                          butyl methacrylate 30                                                         methyl methacrylate                                                                              30                                                         ______________________________________                                    

EXAMPLE 15

The procedure of Example 1 is repeated except for the difference thatthe copolymer is formed from the following materials:

    ______________________________________                                        Reactants           Percent by Weight                                         ______________________________________                                        glycidyl methacrylate                                                                             15                                                        methacrylamide      5                                                         hexyl acrylate      5                                                         2-ethylhexyl methacrylate                                                                         10                                                        butyl acrylate      10                                                        methyl methacrylate 55                                                        ______________________________________                                    

EXAMPLE 16

The procedure of Example 1 is repeated except for the difference thatthe copolymer is formed from the following materials:

    ______________________________________                                        Reactants          Percent by Weight                                          ______________________________________                                        glycidyl methacrylate                                                                            15                                                         methacrylamide     5                                                          alpha methyl styrene                                                                             5                                                          2-ethylhexyl acrylate                                                                            5                                                          vinyl acetate      5                                                          methacrylonitrile  5                                                          butyl methacrylate 20                                                         methyl methacrylate                                                                              40                                                         ______________________________________                                    

EXAMPLE 17

The procedure of Example 7 is repeated with the two exceptions that (1)an equimolar amount itaconic anhydride is substituted for the succinicanhydride and (2) a functionally equivalent amount of poly (dimethylsiloxane) is substituted for the poly (lauryl acrylate).

EXAMPLE 18

The procedure of Example 7 is repeated with the exceptions that anequimolar amount of phthalic anhydride is substituted for the succinicanhydride and (2) a functionally equivalent amount of10-hydroxyoctadeocanoic acid in place of 2-hydroxyoctadeocanoic acid.

EXAMPLE 19

The procedure of Example 7 is repeated with the exception that anequimolar amount of p-chlorophthalic anhydride is substituted for thesuccinic anhydride.

EXAMPLE 20

The procedure of Example 7 is repeated with the exception that anequimolar amount of tetrahydrophthalic anhydride is substituted for thesuccinic anhydride.

EXAMPLE 21

The procedure of Example 1 is repeated with the exception that anequimolar amount of poly (adipic anhydride) is substituted for the poly(azelaic anhydride).

EXAMPLE 22

The process of Example 1 is repeated with the single difference that theflow control agent, poly (2-ethylhexyl acrylate) is employed in anamount equal to 0.05 weight percent of the powder mixture.

EXAMPLE 23

The process of Example 1 is repeated with the single difference that theflow control agent, poly (2-ethylhexyl acrylate) is employed in anamount equal to 1.0 weight percent of the powder mixture.

EXAMPLE 24

The process of Example 1 is repeated with the single difference that theflow control agent, poly (2-ethylhexyl acrylate) is employed in anamount equal to 2.0 weight percent of the powder mixture.

EXAMPLE 25

The process of Example 1 is repeated with the single difference that theflow control agent, poly (2-ethylhexyl acrylate) is employed in anamount equal to 4.0 weight percent of the powder mixture.

Many modifications of this invention will be apparent to those skilledin the art in view of this specification. It is intended that all suchmodifications which fall within the scope of this invention be includedwithin the appended claims.

We claim:
 1. In a thermosettable powder paint which exclusive ofpigments, catalysts, antistatic agents, plasticizers and flow controlagents, the same being conventional non-reactive additives to athermosettable powder paint, consists essentially of a coreactableparticulate mixture of1. an epoxy-functional copolymer consistingessentially of about 5 to about 20 weight percent of a monoethylenicallyunsaturated glycidyl ester of an unsaturated acid and about 80 to about95 weight percent of other monoethylenically unsaturated monomers, andhaving a glass transition temperature in the range of about 40° to about90° C. and a molecular weight (M_(n)) in the range of about 1500 toabout 15,000 and
 2. an anhydride crosslinking agent selected from thegroup consisting ofa. monomeric anhydrides of dicarboxylic acids and b.homopolymers of monomeric anhydrides of dicarboxylic acids, and presentin an amount that provides about 0.3 to about 1.2 anhydride groups foreach functional group on said copolymer, the functional groups of saidcopolymer being limited to epoxy groups and amide groups,the improvementwherein A. said copolymer is qualitatively difunctional and said othermonoethylenically unsaturated monomers consist essentially of analpha-beta olefinically unsaturated amide in an amount comprising about2 to about 10 weight percent of said copolymer and monoethylenicallyunsaturated monomers consisting essentially of monofunctional monomersselected from the group consisting of esters of a C₁ - C₈ monohydricalcohol and acrylic acid, esters of a C₁ - C₈ monohydric alcohol andmethacrylic acid and C₈ - C₁₂ monovinyl hydrocarbons, and B. there is inadmixture with said copolymer and said anhydride crosslinking agent ahydroxy carboxylic acid having a melting point in the range of about 40°to about 150° C. in an amount such as to provide about 0.1 to about 0.4carboxyl groups per functional group on said copolymer.
 2. A powderpaint in accordance with claim 1 wherein said monomeric anhydrides havemelting points in the range of about 35° to about 140° C. and saidhomopolymers of monomeric anhydrides have molecular weight (M_(n)) inthe range of about 1,000 to about 5,000.
 3. A powder paint in accordancewith claim 1 wherein said alpha-beta olefinically unsaturated amide isan amide selected from acrylamide and methacrylamide.
 4. A powder paintin accordance with claim 1 wherein said glycidyl ester is an esterselected from glycidyl acrylate and glycidyl methacrylate.